First-principle study of structural, electronic and elastic properties of SrS, SrSe and SrTe under pressure

The full-potential linearized augmented plane wave method (FP-LAPW) within the generalized gradient approximation (GGA) is used to calculate the electronic band structures and the total energies of SrS, SrSe and SrTe in NaCl- and CsCl-type structures. The latter provide us with the ground state properties such as lattice parameter, bulk modulus and its pressure derivative, elastic constants and the structural phase stability of these compounds. The transition pressures at which these compounds undergo structural phase transition from NaCl to CsCl phase are calculated. The energy band gaps at room conditions in NaCl structure and volume dependence of the band gaps in the CsCl structure are presented. The pressure and volume at which band overlap metallization occurs are also determined. The ground state properties, the transition and metallization pressures (volumes) are found to agree with the experimental and other theoretical results. The elastic constants at room conditions in both NaCl and CsCl structures are calculated and compared with the available theoretical results for SrSe while, for SrS and SrTe, the elastic constants are not available